The announcement was made after NFL commissioner Roger Goodell's meeting with Vick earlier today, which reportedly lasted the better part of an hour. After the meeting with Vick, Goodell met with the man who's acting as his mentor, former NFL coach Tony Dungy, for 45 minutes.

"Hopefully we can have a success story here, which would be good for society in general," Goodell told ESPN of Vick. "He's realistic about the challenges ahead. And anxious to play football." From ESPN:

During their meeting Thursday, the topic of Vick's past experiences and
why he got involved in dog-fighting came up. One of Vick's
representatives was explaining it, when Vick stepped in and took
responsibility. "He was genuinely remorseful," Goodell said.

Goodell said he did discuss with Vick the report that he was seen
drinking an alcoholic beverage in a restaurant at the hotel where he
was staying. Goodell said it was not a violation of his probation.

"It highlights the tremendous microscope this man is under," Goodell
said. "He understands he has little margin for error. It served as a
useful lesson."

When Goodell first announced that Vick would be allowed to return to the NFL, he said he wouldn't consider offering him full reinstatement until the sixth week of league play, in mid-October. It's unclear what caused him to change his mind and push up the date of his official reinstatement.